Large computer systems, as well as other electrical equipment, generate great quantities of heat which must be removed from the computer. This is typically done by blowing ambient air through the computer housing from an air inlet in the housing, along an air path within the housing and out an air outlet. One of the problems with conventional forced air cooling systems is that the ambient air temperature often increases because of the heat generated by the computer. Recognizing this, it is quite important that the temperature of the air in entering of the computer housing be sufficiently low to provide proper cooling. If the inlet air temperature exceeds a chosen value, for example 40.degree. C. then, based on the design of the computer, the air may not properly cool the components, which can result in an overheating failure.